Assemblies and methods for illuminating a display

ABSTRACT

A computer display is disclosed. The computer display includes a LCD housing, a light source coupled to the LCD housing, and a LCD coupled to the LCD housing. The LCD housing conducts light from the light source to the LCD. A method for conducting light is also disclosed. The method includes generating light and conducting the generated light through a LCD housing.

RELATED APPLICATION

This application is a continuation of and claims priority benefit under35 U.S.C. § 120 from U.S. patent application Ser. No. 08/835,732, filedon Apr. 11, 1997, which is hereby incorporated herein by reference inits entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to flat panel display systems.More particularly, the present invention relates to methods andapparatus for backlighting a liquid crystal display (LCD). Even moreparticularly, the present invention relates to backlighting a LCD on alaptop computer.

2. Description of the Related Art

A conventional laptop computer, such as the laptop computer shown inFIG. 1, utilizes a “fliptop” display to display computer data. Thefliptop display is generally perpendicular to the body of the laptopcomputer when the laptop is in use, allowing the user to view thedisplayed computer data. When the laptop computer is not in use, thefliptop display is folded down into a closed position so that it issubstantially parallel to the body of the computer.

The prior art fliptop display assemblies include a LCD housing. The LCDhousing is typically hinged to the body of the laptop computer andgenerally operates as a protective cover for the LCD module.

Prior art fliptop displays also include a LCD module. The LCD moduleincludes a LCD and a means for “backlighting” the LCD. Backlightingrefers to generating light behind the LCD and uniformly projecting itthrough the LCD. Prior art backlighting techniques generally involve theuse of a light source and a light pipe composed of light transmissivematerial located adjacent to the LCD. U.S. Pat. No. 5,050,946, which isincorporated herein by reference, discusses various light source andlight pipe designs.

A cross sectional view of a conventional fliptop display 2 is shown inFIG. 2. As shown in FIG. 2, the conventional fliptop display 2 includesa LCD housing 10 and a LCD module 15. The LCD housing 10 is composed ofan opaque material (usually plastic) and protects the LCD module 15. TheLCD module 15 is secured within the LCD housing 10 by various commonsecuring means, such as screws, clips, or other frictionally engaging orinterlocking means (not shown). Referring again to FIG. 2, the LCDhousing 10 has a rear portion 12 and top and bottom portions 11.

Referring again to FIG. 2, the LCD module 15 includes a LCD 20, a lightsource 25, and a light pipe 30. The aperture 26 of the light source 25is aligned adjacent to an end of the light pipe 30. As shown in FIG. 2,the light pipe 30 is adjacent to the back surface 21 of the LCD 20. TheLCD 20 is backlit when light generated by the light source 25 isconducted through the light source aperture 26 and coupled into an endof the light pipe 30. As shown in U.S. Pat. No. 5,050,946, the coupledlight may be uniformly diffused throughout the light pipe 30, andprojected toward the back surface 21 of the LCD 20. Some conventionalLCD modules utilize a light pipe 30 with a light-reflective coatingapplied to the back side 31 of the light pipe 30 (not shown). In thismanner, light incident upon the back surface 31 of the light pipe 30will be reflected back into the light pipe 30 for projection toward theLCD 20.

As shown in FIG. 2, the length of the top and bottom portions 11 of theLCD housing 10, and hence the depth D of the fliptop display 2, areroughly defined by the combined thickness of the rear portion 12 of theLCD housing 10 and the LCD module 15.

As shown in FIG. 3, the depth D of the fliptop display 2 is at least thesum of the thickness dl of the rear portion 12 of the LCD housing 10,the diameter d3 of the light source 25, and some fractional portion ofthe thickness d5 of the LCD 20. In situations where the diameter d3 ofthe light source 25 is equal to the thickness d4 of the light pipe 30,the depth D may be the sum of the thicknesses dl, d3 (or d4), and d5.

For example, thickness dl of the rear portion 12 of the LCD housing 10may be 4 mm, the diameter d3 of the light source 25 may be 4 mm and thethicknesses d4 and d5 of the light pipe 30 and the LCD 20 may be 2 mm.As shown in FIG. 3, these dimensions will result in the light source 25extending 1 mm on either side of the light pipe 30. It can be seen thatfor this configuration of components, the depth D of the fliptop display2 will be at least 9 mm and the thickness d2 of the LCD module 15 willbe 5 mm. In situations where the diameter d3 of the light source 25 isequal to the thickness d4 of the light pipe 30, the depth D of thefliptop display 2 will be 8 mm and the thickness d2 of the LCD module 15will be 4 mm.

In the laptop computer industry, it is always desirable to reduce thesize and weight of the laptop computer and its component parts. It isalso desirable to minimize the number of parts. Thus, there exists aneed for a thinner, less complex, and lighter fliptop display.

SUMMARY OF THE INVENTION

One embodiment of the present invention is a computer display. Thecomputer display includes a LCD housing, a light source coupled to theLCD housing, and a LCD coupled to the LCD housing. In this embodiment,the LCD housing conducts light from the light source to the LCD.

Another embodiment of the invention is a method for conducting light.The method includes generating light and conducting the generated lightthrough a LCD housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a laptop computer.

FIG. 2 is a cross sectional view of a prior art fliptop display for alaptop computer.

FIG. 3 is a close up view of the lower portion of FIG. 2.

FIG. 4 is a cross sectional view of a novel fliptop display of a laptopcomputer.

FIG. 5 is a close up view of the lower portion of FIG. 4.

FIG. 6 is a close up view of an alternative embodiment of the lowerportion of FIG. 4.

FIG. 7 is a cross sectional view of an alternative embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 4 illustrates a cross sectional view of a novel fliptop display 5.The fliptop display 5 includes a planar LCD module 70 and a generallyplanar LCD housing 50. The LCD module 70, which includes a planar LCD71, is secured in the LCD housing 50 by various common securing means,such as screws, clips, or other frictionally engaging or interlockingmeans (not shown).

The LCD housing 50 is composed of a translucent material that functionsas a light pipe. For example, the LCD housing 50 may be formed from anABS plastic such as Lexan™ from General Electric. The LCD housing 50 mayinclude a planar rear portion 54 and top and bottom portions 55. Asshown in FIG. 4, a light source 60 may be partially embedded in orenclosed in the LCD housing 50. The light source 60 may be secured inthe LCD housing 50 by friction fit or by various common securing means,such as screws, clips, or other frictionally engaging or interlockingmeans (not shown). The LCD housing 50 may also have a light-reflectivecoating 53 applied to its outer surface 58. The light-reflective coating53, may be composed of aluminum or a variety of metallic or otherreflective substances. The light-reflective coating 53 reflects lightincident upon it back into the LCD housing 50 for projection to the LCDmodule 70. The reflective coating 53, when made of materials such aselectroless chrome followed by 40 to 50 (inches of copper, then nickelplating of 10 (inches may also operate to minimize EMI emissions fromthe fliptop display 5.) Alternatively, a nickel-copper-nickel platingmay be utilized. Because the reflective coating 53 forms the outersurface 58 of the housing 50, it may be desirable to cover it or paintit with a protective layer 56 composed of a material such as soft touchpolyethylene paint, that resists scratching and preserves its desiredoptical qualities.

During operation of the fliptop display 5, the light source 60 generateslight. This light is conducted through the LCD housing 50. The conductedlight is then projected into the back surface 72 of the LCD module 70.

FIG. 5 shows a close-up view of the lower portion of FIG. 4. In FIG. 5,the rear portion 54 of the LCD housing 50 has a thickness d6. Thefractional portion of the LCD housing 50 between its outer surface 58and the light source 60 has a thickness d7. (The light-reflective coat53 and its protective layer 56 add a negligible thickness). The lightsource 60 depicted in FIG. 5 is a cold cathode fluorescent lamp that hasa diameter d3. For maximum light coupling, the cold cathode fluorescentlamp 60 may be embedded in the LCD housing 50 so that the aperture 61 ofthe cold cathode fluorescent lamp 60 is completely adjacent to the LCDhousing 50. The LCD module 70, which has a thickness d8, may be adjacentto the inner surface 52 of the LCD housing 50. Thus, it can be seen fromFIG. 5, that the depth D of the fliptop display 5, closely approximatesthe sum of the thickness d7 of the fractional portion of the LCD housing50 between its outer surface 58 and the light source 60, the diameter d3of the light source, and some fraction of the thickness d8 of the LCDmodule 70. It can also be seen that the depth D of the fliptop display 5closely approximates the sum of the thickness d6 of the rear portion 54of the LCD housing 50 and the thickness d8 of the LCD 71.

For example, using the dimensions previously discussed for thesecomponents, the thickness d8 of the LCD 71 is 2 mm and the thickness d6of the LCD housing 50 is 4 mm. To provide maximum light coupling, thelight source 60 with a 2 mm aperture 61 will be embedded in the LCDhousing 50 so that 1 mm of diameter protrudes from the assembly.Accordingly, the thickness d7 will be 1 mm, and the fraction of thethickness d8 contributing to the depth D of the fliptop display 5 willbe 1 mm. Thus, it can be seen that the depth D of the fliptop display 5is now 6 mm. This depth D is 25% less than the depth of conventionalfliptop displays.

Another embodiment of the present invention is shown in FIG. 6. Thisembodiment, includes an omnidirectional light source 62. A reflector 63is used to direct incident light generated by the omnidirectional lightsource 62 back into the LCD housing 50. As shown by the path traveled bylight ray A, the light-reflective coating 53 will internally reflectlight conducted into the bottom portion 55 of the LCD housing 50 untilthe light is eventually directed toward the rear surface 72 of the LCDmodule 70. Since all internal reflections will inherently have a lossyeffect on the incident light, the junction of the rear portion 54 andthe bottom portion 55 of the LCD housing 50 may be geometrically shapedso that light is reflected into the rear portion 54 with a minimumamount of internal reflections. In this embodiment, the light source 62need not be enclosed in the LCD housing 50 to the extent of the coldcathode fluorescent lamp 60 of FIG. 5. In situations where a greaterthickness d7 is required to protect the light source 62, the lightsource 62 may be enclosed in the LCD housing 50 at a variety of depths.

Still another embodiment of the present invention is shown in FIG. 7. Inthis embodiment, the light source 62 and the reflector 63 may be locatedin the middle of the rear portion 54 of the LCD housing 50. The lightsource 62 may be partially enclosed in the LCD housing 50. Theprotrusion of the light source 62 (and the reflector 63) from the LCDhousing 50 creates a gap 66 between the rear surface 72 of the LCDmodule 70 and the inner surface 52 of the LCD housing 50. This resultsin a larger gap 66 than required solely to accommodate the protrusion ofthe light source 62 from the LCD housing 50.

The gap 66 may be purposely designed into the fliptop display 5 as adesign tradeoff between depth D and lighting efficiency. While the depthD of the fliptop display 5 will be increased, lighting efficiency may beimproved. The addition of the gap 66 will provide the light with agreater depth d in which to diffuse before being incident upon the rearsurface 72 of the LCD 71. This may provide better illumination of theLCD 71 toward the top and bottom portions 55 of the LCD housing 50.

Yet another embodiment is shown in FIG. 8. In this embodiment, thethickness d6 of the rear portion 54 of the LCD housing 50 in FIG. 7 maybe increased in order to strengthen the LCD housing 50. For example,using the typical dimensions previously discussed for the variousfliptop display components, the thickness d6 may be increased up to 2 mmbefore the fliptop display 5 has the same depth D as in the prior art.As shown in FIG. 8, the depth d of the gap 66 is correspondinglyreduced.

In yet another embodiment, the LCD housing 50 can be designed to displaya variety of ornamental effects. In this embodiment, areas of thelight-reflective coating 53 can be masked or removed by scoring or byetching so that light incident upon these areas is no longer reflectedback into the LCD housing 50, but instead is conducted out of the LCDhousing 50. The protective layer 56 would also typically be similarlyscored or etched in order to allow the light to leave the LCD housing50. In this manner, text, company logos, trademarks, or other designsmay be illuminated.

With respect to the embodiments described herein, it can be seen thatthe present inventions incorporation of the light pipe function into theLCD housing provides the laptop computer designer with greater designflexibility. The potential reduction in depth D of the fliptop displayprovides the laptop computer designer with a variety of configurationsfor the light source, LCD, and LCD housing assembly. The laptop computerdesigner may configure these components in a variety of ways resultingin a fliptop display depth D that is less than or equal to the width ofthe prior art fliptop display assembly. Additionally, the size and/orweight of the LCD module may substantially reduced. While this designflexibility has been demonstrated in the description of the preferredembodiments, it is clear that many other modifications, changes,variations, and substitutions are within the scope of this invention.

1. An assembly for illuminating a display, the assembly comprising: a LCD; a LCD housing made in a single piece from a single light transmissive material, wherein the LCD housing is coupled to the LCD and is configured to protect the LCD; at least one light source substantially embedded in the LCD housing, wherein the LCD housing functions as a light pipe for conducting light from the at least one light source directly to the LCD; and a reflective coating on at least a portion of a surface of the LCD housing, wherein light from the at least one light source is reflected by the reflective coating.
 2. The assembly of claim 1, wherein the single light transmissive material has the same light transmissive characteristics throughout.
 3. The assembly of claim 1, wherein the reflective coating comprises a material that attenuates electromagnetic interference (EMI) emissions.
 4. The assembly of claim 3, wherein the LCD housing includes an inner surface and wherein the LCD is adjacent to the inner surface.
 5. The assembly of claim 3, wherein the at least one light source comprises a cold cathode fluorescent lamp.
 6. The assembly of claim 3, wherein the reflective coating includes a metallic coating.
 7. The assembly of claim 1, wherein the LCD housing comprises a plastic.
 8. The assembly of claim 1, wherein the at least one light source comprises an omnidirectional light source.
 9. The assembly of claim 1, wherein the reflective coating comprises etched portions to allow light to leave the LCD housing.
 10. The assembly of claim 1, wherein the LCD housing includes a lower end and an upper end, and wherein the at least one light source is located at one of the lower end and the upper end.
 11. The assembly of claim 1, wherein the LCD housing is configured to protect at least two sides of the LCD.
 12. A method for conducting light in a device having a LCD and a LCD housing, the method comprising: generating light from at least one light source substantially enclosed within a LCD housing at least partially coated with a reflective material; and conducting the generated light through the LCD housing directly to a LCD, wherein the LCD housing is made by a unitary construction of a single translucent material configured to function as a light pipe for illuminating the LCD, and wherein the LCD housing is further configured to protect the LCD.
 13. The method of claim 12, wherein generating the light includes generating light with a cold cathode fluorescent lamp.
 14. The method of claim 12, additionally comprising reducing electromagnetic (EMI) emissions with the reflective material.
 15. The method of claim 12, wherein the single translucent material has the same light transmissive characteristic throughout.
 16. The method of claim 12, wherein said conducting further includes reflecting at least a first portion of the light with the reflective material.
 17. The method of claim 16, additionally comprising allowing a second portion of the light to leave the LCD housing through etched portions of the reflective material.
 18. A display comprising: means for displaying data; means for housing the display means, the housing means made in a single piece from a single light transmissive material and coupled to the display means; means for generating light for the display means, wherein the generating means is substantially embedded in the housing means, the housing means structured to function as a light pipe to conduct light generated by the generating means directly to the display means; and means for reflecting at least a portion of the light generated by the generating means, wherein the reflecting means coats at least a portion of a surface of the housing means.
 19. The display of claim 18, wherein the single light transmissive material has the same light transmissive characteristics throughout.
 20. The display of claim 18, wherein the housing means protects at least three sides of the display means. 